Elizabeth A. Ahearn Gardner C. Bent Jennifer B. Fair Caroline F. Mazo 20250422 tabular digital data Northeast Region U.S. Geological Survey https://doi.org/10.5066/P147SYMU Elizabeth A. Ahearn Gardner C. Bent 20250723 publication Scientific Investigations Report 2025-5027 Reston, VA U.S. Geological Survey USGS Scientific Investigation Series, New England Water Science Center https://doi.org/10.3133/sir20255027 The U.S. Geological Survey (USGS), in cooperation with the Connecticut Department of Energy and Environmental Protection and the Connecticut Department of Transportation, calculated select streamflow statistics and basin characteristics. This U.S. Geological Survey (USGS) data release provides select streamflow statistics and basin characteristics for 118 streamgages in Connecticut and adjacent states compiled using data through water year 2022. A subset of the data from select streamgages with minimally altered flow conditions was used in the development of statewide regression equations to estimate: 1-, 5-, 10-, 25-, 50-, 75-, 90-, 99-percent flow durations; 7-day, 10-year low-flow frequency (7Q10) and 30-day, 2-year low-flow frequency (30Q2); mean flow, spring mean flow, and harmonic mean flow; and monthly and seasonal flow durations ranging from 1- to 99-percent for six bioperiods ⸺ salmonid spawning (November), overwinter (December–February), habitat forming (March-April), clupeid spawning (May), resident spawning (June), and rearing and growth (July–October). The data used in this study were compiled to help provide federal and state governments with the information needed to manage their water resources. This data release contains (1) data files in comma-separated values (.CSV) format of the streamflow statistics and basin characteristics for 118 streamgages, and (2) the USGS Weighted Multiple-Linear Regression (WREG, version 3.0) input and output data files in text format for four sets of regressions (n-day frequency, flow durations, bioperiod flow durations, and mean flows). The WREG input and output files for 47 statewide regression equations are in zipped folders. The updated streamflow statistics and regression equations provided in this data release support regulatory agencies and help state agencies effectively manage water resources in Connecticut. The zipped files contain README text (.txt) files that describe the data and data files from the regression analysis. Files can be viewed in a spreadsheet program, such as Microsoft Excel or a text-type app (text editor) such as Notepad. Excel will remove the leading zeros of the streamgage identification number, unless the column with the streamgage identification number is formatted as text prior to viewing the file. A “txt” file will retain leading zeros when opened with text-type apps such as Notepad. Note that some text editors may not display the input files in an easy-to-read format, with properly aligned columns. File can be best viewed in an easy-to-read format, with properly aligned columns by opening the data in Microsoft Excel as tab-delimited. 19121001 20220930 observed Complete None planned -74.2896 -69.7632 42.9645 40.9600 USGS Thesaurus regression analysis streamflow flow duration n-day frequency harmonic mean mean flow USGS Metadata Identifier USGS:6626a98ed34ea70bd5efa08a Common geographic areas Connecticut None. Please see 'Distribution Info' for details. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Elizabeth A Ahearn U.S Geological Survey Hydrologist mailing and physical

33 Main Street

East Hartford CT 06118-0000 860-291-6745 eaahearn@usgs.gov No formal attribute accuracy tests were conducted. No formal attribute accuracy tests were conducted. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. No formal positional accuracy tests were conducted. No formal positional accuracy tests were conducted. Stone, J.R., Stone, B.D., DiGiacomo-Cohen, M.L., and Mabee, S.B. 2018 vector digital data Reston, VA U.S. Geological Survey Stone, J.R., Stone, B.D., DiGiacomo-Cohen, M.L., and Mabee, S.B., comps., 2018, Surficial materials of Massachusetts—A 1:24,000-scale geologic map database: U.S. Geological Survey Scientific Investigations Map 3402, 189 sheets, scale 1:24,000; index map, scale 1:250,000; 58-p. pamphlet; and geodatabase files. http://pubs.usgs.gov/sim/2018/3402/ http://pubs.usgs.gov/sim/2018/3402/ Digital and/or Hardcopy 20221231 publication date Massachusetts surficial geology Provided surficial geology data for the state of Massachusetts. Stone, J.R., Schafer, J.P., London, E.H. and Thompson, W.B. 1992 vector digital data Reston, VA U.S. Geological Survey Surficial materials map of Connecticut digitized by CTDEEP. https://ct-deep-gis-open-data-website-ctdeep.hub.arcgis.com/datasets/CTDEEP::surficial-materials/about Digital and/or Hardcopy 20221231 application date Connecticut surficial materials map Provided surficial geology data for the state of Connecticut. Environmental Data Center, University of Rhode Island, Kingston, Rhode Island 1989 vector digital data Kingston, Rhode Island RIGIS https://www.rigis.org/datasets/edc::glacial-deposits/about http://data.rigis.org/geo/glacial.zip Digital and/or Hardcopy 20221231 application date Rhode Island surficial geology Provided surficial geology information. NYS Museum / NYS Geological Survey 1999 vector digital data Albany, NY NYS Museum Technology Center https://www.nysm.nysed.gov/research-collections/geology/gis Digital and/or Hardcopy 20221231 publication date New York surficial geology Provided surficial geology information for the state of New York. Natural Resources Conservation Service 20200609 vector digital data Fort Worth, Texas U.S. Department of Agriculture, Natural Resources Conservation Service Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Soil Survey Geographic (SSURGO) Database for Connecticut, Massachusetts, Rhode Island, New Hampshire, Vermont, and New York. Available online. Accessed on June, 25, 2020. https://websoilsurvey.sc.egov.usda.gov/ Digital and/or Hardcopy 20221231 application date Soil survey geographic database Dataset provided information on hydrologic soil groups. The PRISM Group at Oregon State University 20120710 raster digital data Corvallis, OR, USA PRISM Climate Group at Oregon State University http://www.prism.oregonstate.edu Digital and/or Hardcopy 19810101 20101231 publication date Climatic data PRISM 1981-2010 Parameter-elevation regressions on independent slopes model climate mapping system: Oregon State University, PRISM Climate Group U.S. Geological Survey 2018 vector digital data U.S. Geological Survey, 2019, National Hydrography Dataset (ver. USGS National Hydrography Dataset Best Resolution (NHD) for Hydrologic Unit (HU) 4 - 2001 (published 20191002)), accessed October 2, 2021 at https://www.usgs.gov/national-hydrography/access-national-hydrography-products https://www.usgs.gov/national-hydrography/access-national-hydrography-products Digital and/or Hardcopy 20221231 application date National hydrography dataset Provided hydrological data used in statistical model. U.S. Geological Survey 2021 raster digital data Reston, VA U.S. Geological Survey U.S. Geological Survey, 2019, National Elevation Dataset. Accessed May 28, 2021. https://apps.nationalmap.gov/downloader/ Digital and/or Hardcopy 20221231 application date National Elevation Dataset Provided elevation data used in statistical model. U.S. Geological Survey 2016 raster digital data Sioux Falls, SD U.S. Geological Survey National Land Cover Database (NLCD) 2019 Products. U.S. Geological Survey data release, https://doi.org/10.5066/P937PN4Z https://www.mrlc.gov/data Digital and/or Hardcopy 20221231 publication date National land cover database 2016 Provided land use information for use in regression model. U.S. Geological Survey 20190304 2019 application/service Reston, VA U.S. Geological Survey U.S. Geological Survey, 2019, The StreamStats program, online at https://streamstats.usgs.gov/ss/, accessed in 2019. https://streamstats.usgs.gov/ss/ Digital and/or Hardcopy 20221231 application date StreamStat Provided watershed basin boundaries at streamgaging locations. Paul M Barlow Amy R McHugh Julie E Kiang Tong Zhai Paul Hummel Paul B Duda Scott Hinz 20220504 publication https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/p13vdnak Digital and/or Hardcopy 20221231 application date Hydrologic Toolbox software Streamflow data collected through water year 2022 at USGS streamgages with 10 or more years of record were compiled from USGS NWIS (http://nwis.waterdata.usgs.gov/usa/nwis/discharge). The USGS statistical software “Hydrologic Toolbox” was used to compute flow durations, low-flow frequencies, and mean flow statistics (Barlow and others, 2022) for streamgages. 20220820 Basin characteristics for streamgages were compiled using publicly available geospatial data layers. The geospatial data layers for calculation of topology related characteristics of the drainage basins are total length of streams data are from the National Hydrography Dataset Plus High Resolution (NHDPlus HR) (U.S. Geological Survey, 2023a) and elevation data, also used for basin slope calculations, are from USGS 3DEP (U.S. Geological Survey, 2023b). Hydrologic soil group data are from the Natural Resources Conservation Service (NRCS) Soil Survey Geographic database (SSURGO) (Natural Resources Conservation Service, 2022). Surficial-geology data (1:24,000 scale) are from Connecticut Department of Energy and Environment Protection (CTDEEP) (2022), Massachusetts Office of Geographic Information (MassGIS) (2022), New York State Museum (2022), and Rhode Island Geographic Information System (RIGIS) (2022). Climatic data (monthly and annual precipitation and annual temperature 1981–2010) are from the Parameter-Elevation Relationships on Independent Slopes Model (PRISM) Climate Group, Oregon State University (2021). Land-cover data are from the National Land Cover Database (NLCD) 2016 (Multi-Resolution Land Characteristics Consortium, 2022). The basin boundaries for streamgages were compiled using USGS StreamStats web application, online at https://streamstats.usgs.gov/ss/, accessed on June 2022. In ArcGIS Pro (version 3.0) spatial analyst tools were used to tabulate and summarize the basin characteristics. 20220606 Regional regression analysis was used to develop 47 equations to estimate selected streamflow statistics by relating the flow statistics to basin characteristics at streamgages in and near Connecticut. The methodology and software used in the development of the regression equations is described in Ahearn and Bent, 2024. A detailed description of file content and format can be found in USGS Techniques and Methods 4-A8, User’s Guide to the Weighted-Multiple-Linear Regression Program. 20230920 Basin_characteristics.csv Comma-separated values (CSV) file containing data. Producer Defined Sta_ID USGS streamgage number Producer Defined Each site in the USGS database has a unique 8-to 10-digit identification number. https://waterdata.usgs.gov/nwis Sta_name Streamgage name and location Producer Defined name and location of streamgage https://waterdata.usgs.gov/nwis DA Upstream drainage area of streamgage Producer Defined drainage area of streamgage Lat Latitude of streamgage, decimal degrees referenced to NAD 83 Producer Defined streamgage latitude referenced to NAD83 Long Longitude of streamgage, decimal degrees referenced to NAD 83 Producer Defined streamgage longitude (NAD83) referenced to NAD83 Lat_cent Latitude of streamgage basin centroid, decimal degrees referenced to NAD 83 Producer Defined centroid latitude of streamgage basin referenced to NAD83 Long_cent Longitude of streamgage basin centroid, decimal degrees referenced to NAD83 Producer Defined centroid longitude of streamgage basin referenced to NAD 83 Min_basin_elev Minimum basin elevation, in feet relative to NAVD88 Producer Defined 0.591457784 1139.651978 feet Max_basin_elev Maximum basin elevation, in feet relative to NAVD88 Producer Defined 366.2906189 2619.995117 feet B_Relief Basin relief (maximum basin elevation - minimum basin elevation) Producer Defined 259.1088257 2590.402267 feet MBElev Mean basin elevation, in feet relative to NAVD88 Producer Defined 128.2956253 1373.465987 feet GW_head Groundwater head (mean elevation - minimum elevation), in feet Producer Defined 60.8071857 937.2513955 feet Relief_ratio Relief ratio ((mean basin elevation - minimum basin elevation) / (maximum basin elevation - minimum basin elevation) Producer Defined 0.156598503 0.655180107 MBSlope Mean basin slope, in percent Producer Defined 4.897554017 17.3331956 percent 0.0001 TotStrLen Total length of stream, in miles Producer Defined 0.780085932 3305.950018 miles StrDen Stream density (total length of streams/drainage area), in miles per square miles Producer Defined 1.249621721 4.421614544 miles per square miles 0.0001 10_85slope Main channel slope between 10th and 85th percent of length, in feet per mile Producer Defined 5.733072498 238.3180016 feet per mile 0.0001 HYDGRP_A SSURGO hydrologic soils type A, in percent Producer Defined 0.0 49.36302731 percent 0.0001 HYDGRP_B SSURGO hydrologic soils type B, in percent Producer Defined 2.92378002 64.16676651 percent 0.0001 HYDGRP_C SSURGO hydrologic soils type C, in percent Producer Defined 0.658641689 47.68737134 percent 0.0001 HYDGRP_D SSURGO hydrologic soils type D, in percent Producer Defined 2.321175522 68.21801857 percent HYDGRP_AD SSURGO hydrologic soils type AD, in percent Producer Defined 0.0 5.920328344 percent HYDGRP_BD SSURGO hydrologic soils type BD, in percent Producer Defined 0.414570621 26.1854695 percent HYDGRP_CD SSURGO hydrologic soils type CD, in percent Producer Defined 1.915913356 34.46099437 percent HYDGRP_W SSURGO hydrologic category water, in percent Producer Defined 0.0 12.60608325 percent GRP1 Surficial geology type, stratified drift and sand and gravel, in percent Producer Defined 0.0 56.90894403 percent GRP2 Surficial geology type, alluvium and fluvial, in percent Producer Defined 0.0 10.8621333 percent GRP3 Surficial geology type, fines geo-lacustrine, in percent Producer Defined 0.0 34.52595061 percent GRP4 Surficial geology type, swamp and marsh, in percent Producer Defined 0.0 20.70624898 percent GRP5 Surficial geology type, till and moraine, in percent Producer Defined 39.98534889 98.84448378 percent GRP6 Surficial geology type, bedrock and fill, in percent Producer Defined 0.0 28.73209027 percent GRP7 Surficial geology type, water, in percent Producer Defined 0.0 10.21003884 percent Temp Temperature 1981–2010, Mean annual minimum (degrees Fahrenheit) Producer Defined 45.35417476 51.76849998 degrees Fahrenheit Precip Precipitation 1981–2010, Mean annual (inches) Producer Defined 45.76307017 53.2165363 inches Jan_precip Precipitation 1981–2010, Mean monthly for January, in inches Producer Defined 3.129792435 4.079224421 inches Feb_precip Precipitation 1981–2010, Mean monthly for Febuary, in inches Producer Defined 2.770126357 3.810029577 inches Mar_precip Precipitation 1981–2010, Mean monthly for March, in inches Producer Defined 3.346311975 5.19524917 inches Apr_precip Precipitation 1981–2010, Mean monthly for April, in inches Producer Defined 3.720344795 4.801861056 inches May_precip Precipitation 1981–2010, Mean monthly for May, resident clupeid bioperiod, in inches Producer Defined 3.461793348 4.836577804 inches Jun_precip Precipitation 1981–2010, Mean monthly for June, resident spawning bioperiod, in inches Producer Defined 3.767314805 4.805314973 inches Jul_precip Precipitation 1981–2010, Mean monthly for July, in inches Producer Defined 3.624710673 5.086323472 inches Aug_precip Precipitation 1981–2010, Mean monthly for August, in inches Producer Defined 3.829944544 4.612746506 inches Sep_precip Precipitation 1981–2010, Mean monthly for September, in inches Producer Defined 3.832775607 4.659048894 inches Oct_precip Precipitation 1981–2010, Mean monthly for October, in inches Producer Defined 4.070897846 5.243360919 inches Nov_precip Precipitation 1981–2010, Mean monthly for November, salmonid bioperiod, in inches Producer Defined 3.699238254 4.811842039 inches Dec_precip Precipitation 1981–2010, Mean monthly for December, in inches Producer Defined 3.41142353 4.653925389 inches Precip_dec_feb Precipitation 1981–2010, Mean seasonal for months December-February, overwinter bioperiod, in inches Producer Defined 3.152032996 4.181059796 inches Precip_mar_apr Precipitation 1981–2010, Mean seasonal for months March-April, habitat forming bioperiod, in inches Producer Defined 3.533328385 4.998555113 inches Precip_jul_oct Precipitation 1981–2010, Mean seasonal for months July-October, rearing and growth bioperiod, in inches Producer Defined 3.916759604 4.729227304 inches OpenSpace Land cover type - Developed, Open Space, in percent Producer Defined Developed, Open Space- areas with a mixture of some constructed materials, but mostly vegetation in the form of lawn grasses. Impervious surfaces account for less than 20% of total cover. These areas most commonly include large-lot single-family housing units, parks, golf courses, and vegetation planted in developed settings for recreation, erosion control, or aesthetic purposes. Low_Intensity Land cover type - Developed, Low Intensity, in percent Producer Defined Developed, Low Intensity- areas with a mixture of constructed materials and vegetation. Impervious surfaces account for 20% to 49% percent of total cover. These areas most commonly include single-family housing units. Med_Intensity Land cover type - Developed, Medium Intensity, in percent Producer Defined Developed, Medium Intensity -areas with a mixture of constructed materials and vegetation. Impervious surfaces account for 50% to 79% of the total cover. These areas most commonly include single-family housing units. High_Intensity Land cover type - Developed, High Intensity, in percent Producer Defined Developed High Intensity-highly developed areas where people reside or work in high numbers. Examples include apartment complexes, row houses and commercial/industrial. Impervious surfaces account for 80% to 100% of the total cover. B_Land Land cover type - Barren Land, in percent Producer Defined Barren Land (Rock/Sand/Clay) - areas of bedrock, desert pavement, scarps, talus, slides, volcanic material, glacial debris, sand dunes, strip mines, gravel pits and other accumulations of earthen material. Generally, vegetation accounts for less than 15% of total cover. D_Forest Land cover type - Deciduous Forest, in percent Producer Defined Deciduous Forest- areas dominated by trees generally greater than 5 meters tall, and greater than 20% of total vegetation cover. More than 75% of the tree species shed foliage simultaneously in response to seasonal change. E_Forest Land cover type - Evergreen Forest, in percent Producer Defined Evergreen Forest- areas dominated by trees generally greater than 5 meters tall, and greater than 20% of total vegetation cover. More than 75% of the tree species maintain their leaves all year. Canopy is never without green foliage. M_Forest Land cover type - Mixed Forest, in percent Producer Defined Mixed Forest- areas dominated by trees generally greater than 5 meters tall, and greater than 20% of total vegetation cover. Neither deciduous nor evergreen species are greater than 75% of total tree cover. Scrub Land cover type - Shrub/Scrub, in percent Producer Defined Shrub/Scrub- areas dominated by shrubs; less than 5 meters tall with shrub canopy typically greater than 20% of total vegetation. This class includes true shrubs, young trees in an early successional stage or trees stunted from environmental conditions. Herbaceous Land cover type - Grassland/Herbaceous, in percent Producer Defined Grassland/Herbaceous- areas dominated by graminoid or herbaceous vegetation, generally greater than 80% of total vegetation. These areas are not subject to intensive management such as tilling but can be utilized for grazing. Pasture Land cover type - Hay/Pasture, in percent Producer Defined Pasture/Hay-areas of grasses, legumes, or grass-legume mixtures planted for livestock grazing or the production of seed or hay crops, typically on a perennial cycle. Pasture/hay vegetation accounts for greater than 20% of total vegetation. Crops Land cover type - Cultivated Crops, in percent Producer Defined Cultivated Crops -areas used for the production of annual crops, such as corn, soybeans, vegetables, tobacco, and cotton, and also perennial woody crops such as orchards and vineyards. Crop vegetation accounts for greater than 20% of total vegetation. This class also includes all land being actively tilled. W_Wetland Land cover type - Woody Wetlands, in percent Producer Defined Woody Wetlands- areas where forest or shrubland vegetation accounts for greater than 20% of vegetative cover and the soil or substrate is periodically saturated with or covered with water. E_Wetland Land cover type - Emergent Herbaceous Wetlands, in percent Producer Defined Emergent Herbaceous Wetlands- Areas where perennial herbaceous vegetation accounts for greater than 80% of vegetative cover and the soil or substrate is periodically saturated with or covered with water. statistics.csv Comma-separated value (CSV) file containing data. Producer Defined Sta_ID USGS Streamgage number Producer Defined Each site in the USGS database has a unique 8-to 10-digit identification number. https://waterdata.usgs.gov/nwis Sta_name Streamgage name and location Producer Defined Name and location of streamgage https://waterdata.usgs.gov/nwis POR (WY) Period of record at streamgage, in water year Producer Defined Years of record at the streamgage used in deriving select streamflow statistics, in water years (October 1 through September 30) AnnMEAN Mean flow, in cubic feet per second Producer Defined 1.58 2712.74 cubic feet per second 0.01 SprMEAN Spring (March and April) mean flow, in cubic feet per second. Producer Defined 2.50 4918.60 cubic feet per second 0.01 HarMEAN Harmonic mean, in cubic feet per second Producer Defined 1.01 779.20 cubic feet per second 0.01 FD1 1-percent flow duration, in cubic feet per second Producer Defined 4.16 12966.0 cubic feet per second 0.01 FD5 5-percent flow duration, in cubic feet per second Producer Defined 3.1 7430.0 cubic feet per second 0.01 FD10 10-percent flow duration, in cubic feet per second Producer Defined 2.7 5970.0 cubic feet per second 0.01 FD25 25-percent flow duration, in cubic feet per second Producer Defined 2.0 3700.0 cubic feet per second 0.01 FD50 50-percent flow duration, in cubic feet per second Producer Defined 0.94 1958.19 cubic feet per second FD60 60-percent flow duration, in cubic feet per second Producer Defined 0.65 1460.58 cubic feet per second 0.01 FD70 70-percent flow duration, in cubic feet per second Producer Defined 0.41 1041.99 cubic feet per second 0.01 FD75 75-percent flow duration, in cubic feet per second Producer Defined 0.32 849.18 cubic feet per second 0.01 FD80 80-percent flow duration, in cubic feet per second Producer Defined 0.27 656.46 cubic feet per second 0.01 FD85 85-percent flow duration, in cubic feet per second Producer Defined 0.23 471.0 cubic feet per second 0.01 FD90 90-percent flow duration, in cubic feet per second Producer Defined 0.15 364.31 cubic feet per second 0.01 FD95 95-percent flow duration, in cubic feet per second Producer Defined 0.07 274.13 cubic feet per second 0.01 FD98 98-percent flow duration, in cubic feet per second Producer Defined 0.02 208.11 cubic feet per second 0.01 FD99 99-percent flow duration, in cubic feet per second Producer Defined 0.01 180.57 cubic feet per second 0.01 30Q2 30-day, 2-year low-flow frequency, in cubic feet per second Producer Defined 0.18 498.41 cubic feet per second 0.01 30Q10 30-day, 10-year low-flow frequency, in cubic feet per second Producer Defined 0.01 267.05 cubic feet per second 0.01 7Q2 7-day, 2-year low-flow frequency, in cubic feet per second Producer Defined 0.053 326.11 cubic feet per second 0.01 7Q10 7-day, 10-year low-flow frequency, in cubic feet per second Producer Defined 0.01 171.37 cubic feet per second 0.01 Med_7D Median of the 7-consecutive day lowest mean daily flow, in cubic feet per second Producer Defined 0.05 331.57 cubic feet per second 0.01 statistics_bioperiods.csv Comma-separated value (CSV) file containing data. Producer Defined Sta_ID USGS Streamgage number Producer Defined Each site in the USGS database has a unique 8-to 10-digit identification number. https://waterdata.usgs.gov/nwis Sta_name Streamgage name and location Producer Defined name and location of streamgage https://waterdata.usgs.gov/nwis POR (WY) Period of record, in water years Producer Defined Years of record at the streamgage used in deriving select streamflow statistics, in water years (October 1 through September 30) OW_FD1 1-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 3.47 13017.0 cubic feet per second 0.01 OW_FD5 5-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 2.73 7379.5 cubic feet per second 0.01 OW_FD10 10-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 2.31 6115.67 cubic feet per second 0.01 OW_FD25 25-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 1.61 4030.31 cubic feet per second 0.01 OW_FD30 30-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 1.49 3648.27 cubic feet per second 0.01 OW_FD50 50-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 1.19 2519.76 cubic feet per second 0.01 OW_FD70 70-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 0.77 1699.27 cubic feet per second 0.01 OW_FD75 75-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 0.63 1507.41 cubic feet per second 0.01 OW_FD80 80-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 0.49 1279.42 cubic feet per second 0.01 OW_FD90 90-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 0.28 812.65 cubic feet per second 0.01 OW_FD95 95-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 0.19 520.6 cubic feet per second 0.01 OW_FD98 98-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 0.13 394.0 cubic feet per second 0.01 OW_FD99 99-percent flow duration for OverWinter (December-February) bioperiod, in cubic feet per second Producer Defined 0.09 320.4 cubic feet per second 0.01 HAB_FD1 1-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 5.13 17549.0 cubic feet per second 0.01 HAB_FD5 5-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 3.58 11058.89 cubic feet per second 0.01 HAB_FD10 10-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 3.2 8796.0 cubic feet per second 0.01 HAB_FD25 25-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 2.58 6151.25 cubic feet per second 0.01 HAB_FD30 30-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 2.45 5666.0 cubic feet per second 0.01 HAB_FD50 50-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 2.05 4125.56 cubic feet per second 0.01 HAB_FD70 70-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 1.49 3030.22 cubic feet per second 0.01 HAB_FD75 75-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 1.38 2755.0 cubic feet per second 0.01 HAB_FD80 80-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 1.28 2463.45 cubic feet per second 0.01 HAB_FD90 90-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 0.67 1800.44 cubic feet per second 0.01 HAB_FD95 95-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 0.49 1296.75 cubic feet per second 0.01 HAB_FD98 98-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 0.34 815.04 cubic feet per second 0.01 HAB_FD99 99-percent flow duration for Habitat Forming (March-April) bioperiod, in cubic feet per second Producer Defined 0.29 701.06 cubic feet per second 0.01 CLUP_FD1 1-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 4.17 9778.6 cubic feet per second 0.01 CLUP_FD5 5-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 3.49 6906.5 cubic feet per second 0.01 CLUP_FD10 10-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 3.2 6016.0 cubic feet per second 0.01 CLUP_FD25 25-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 2.6 4171.67 cubic feet per second 0.01 CLUP_FD30 30-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 2.25 3893.0 cubic feet per second 0.01 CLUP_FD50 50-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 1.47 2838.33 cubic feet per second 0.01 CLUP_FD70 70-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 1.0 1975.78 cubic feet per second 0.01 CLUP_FD75 75-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 0.92 1776.43 cubic feet per second 0.01 CLUP_FD80 80-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 0.84 1584.75 cubic feet per second 0.01 CLUP_FD90 90-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 0.58 1076.8 cubic feet per second 0.01 CLUP_FD95 95-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 0.47 776.37 cubic feet per second 0.01 CLUP_FD98 98-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 0.35 643.04 cubic feet per second 0.01 CLUP_FD99 99-percent flow duration for Clupeid Spawning (May) bioperiod, in cubic feet per second Producer Defined 0.33 587.1 cubic feet per second 0.01 RES_FD1 1-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 4.14 11140.0 cubic feet per second 0.01 RES_FD5 5-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 3.12 6360.0 cubic feet per second 0.01 RES_FD10 10-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 2.82 4694.0 cubic feet per second 0.01 RES_FD25 25-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 1.48 2905.0 cubic feet per second 0.01 RES_FD30 30-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 1.22 2533.33 cubic feet per second 0.01 RES_FD50 50-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 0.81 1660.0 cubic feet per second 0.01 RES_FD70 70-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 0.52 1080.0 cubic feet per second 0.01 RES_FD75 75-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 0.44 945.33 cubic feet per second 0.01 RES_FD80 80-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 0.37 772.0 cubic feet per second 0.01 RES_FD90 90-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 0.23 497.67 cubic feet per second 0.01 RES_FD95 95-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 0.16 410.67 cubic feet per second 0.01 RES_FD98 98-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 0.11 359.2 cubic feet per second 0.01 RES_FD99 99-percent flow duration for Resident Spawning (June) bioperiod, in cubic feet per second Producer Defined 0.09 335.6 cubic feet per second 0.01 RG_FD1 1-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 3.78 9421.4 cubic feet per second 0.01 RG_FD5 5-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 2.21 4452.25 cubic feet per second 0.01 RG_FD10 10-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 1.72 3029.0 cubic feet per second 0.01 RG_FD25 25-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.76 1585.8 cubic feet per second 0.01 RG_FD30 30-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.64 1360.45 cubic feet per second 0.01 RG_FD50 50-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.3 813.0 cubic feet per second 0.01 RG_FD70 70-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.2 435.74 cubic feet per second 0.01 RG_FD75 75-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.16 393.25 cubic feet per second 0.01 RG_FD80 80-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.11 350.2 cubic feet per second 0.01 RG_FD90 90-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.05 259.38 cubic feet per second 0.01 RG_FD95 95-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.01 212.13 cubic feet per second 0.01 RG_FD98 98-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.004 178.58 cubic feet per second 0.001 RG_FD99 99-percent flow duration for Rearing and Growth (July-October) bioperiod, in cubic feet per second Producer Defined 0.002 157.93 cubic feet per second 0.001 SALM_FD1 1-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 4.7 10426.67 cubic feet per second 0.01 SALM_FD5 5-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 2.56 6506.67 cubic feet per second 0.01 SALM_FD10 10-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 2.01 5163.33 cubic feet per second 0.01 SALM_FD25 25-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 1.31 3276.67 cubic feet per second 0.01 SALM_FD30 30-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 1.2 2942.0 cubic feet per second 0.01 SALM_FD50 50-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 0.69 1807.14 cubic feet per second 0.01 SALM_FD70 70-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 0.33 975.0 cubic feet per second 0.01 SALM_FD75 75-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 0.29 825.67 cubic feet per second 0.01 SALM_FD80 80-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 0.25 656.0 cubic feet per second 0.01 SALM_FD90 90-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 0.16 404.0 cubic feet per second 0.01 SALM_FD95 95-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 0.12 323.5 cubic feet per second 0.01 SALM_FD98 98-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 0.05 256.6 cubic feet per second 0.01 SALM_FD99 99-percent flow duration for Salmonid Spawning (November) bioperiod, in cubic feet per second Producer Defined 0.03 200.95 cubic feet per second 0.01 The data release contains three comma-separated values (csv) files (statistics.csv, statistics_bioperiod.csv, and Basin_characteristics.csv) with updated streamflow statistics and basin characteristics for 118 streamgages. Forty of 118 streamgages were used in the development of statewide regression equations. The file called "statistics.csv" contains select flow statistics for streamgages. The flow statistics include: mean flow, spring mean flow, and harmonic mean flow; 1-, 5-, 10-, 25-, 50-, 60-, 70-, 75-, 80-, 90-, 95-, 98-, and 99-percent flow durations; 7-day, 10-year low- flow frequency (7Q10), 7-day, 2-year low flow frequency (7Q2) , 30-day, 10-year low-flow frequency (30Q10); 30-day, 2-year low-flow frequency (30Q2), and median of the 7-day low flow. The file called "statistics_bioperiods.csv" contains select monthly and seasonal flow durations statistics ranging from 1- to 99-percent for streamgages. The monthly and seasonal flow durations are for 6 bioperiods: Salmonid Spawning (November), Overwinter (December–February), Habitat Forming (March-April), Clupeid Spawning (May), Resident Spawning (June), and Rearing and Growth (July–October). The file called "Basin_characteristics.csv" contains the basin and climatic characteristics of the streamgages. The basin characteristics are given to 7 to 9 decimal places to facilitate calculations that are consistent with the associated regression equations. The data release also contains four zipped folders (Nday_frequency_regression.zip, Mean_flow_regression.zip, Flow_duration_regression.zip, and Bioperiod_flow_duration_regression.zip). The zipped folders contain the Weighted-multiple-linear REGression (WREG) input and output files for the 47 regression models. The input files contain the explanatory and predictor variables. The output files contain the model coefficients, performance metrics, and covariance matrices. A detailed description of the input and output file content and format can be found in USGS Techniques and Methods 4-A8, User’s Guide to the Weighted-Multiple-Linear Regression Program (WREG version 1.0). Ahearn, E.A., Bent G.C, Fair, J.B., and Mazo, C.F., 2024, Data for the development of regression equations for estimating for flow durations, low-flow frequencies, and mean flows in Connecticut using data through water year 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P147SYMU. GS ScienceBase U.S. Geological Survey mailing address

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Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Digital Data https://doi.org/10.5066/P147SYMU None 20250723 U.S. Geological Survey Elizabeth A Ahearn Hydrologist mailing

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East Hartford CT 06118-0000 860-291-6745 eaahearn@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998